Stoker



Nov. 17, 1942. VR, l. BEERs STOKER Filed July 17, 1940 5 Sheets-#Sheet l infill!! MA M Nov. 17, 1942. l R. 1 BEERS 2,302,172

STOKER Filed July 17, 1940 3 Sheets-Sheet 2 cv 1 INVENTOR. ay Z. ,69ers URW,

Ang-:1336s R. L. BEERS Nov. 17, 1942.

STOKER Filed July 17, 1940 3 Sheets-Sheet 3 Um um L ooo onumanauooobaooonnoouooouooou@ aan aeouoouo o e o o ons e n n a o oconooauno acababan 0 o a u u o o o d o a oocoaoooue noeoaoooooovoocoooounoeoooeoo INVENTOR. v @iz/ce I, 66ers @mwN BY @ww ATTOR EYS Patented Nov. 17, 1942 STOKER Royce L. Beers, Birmingham, Mich., assignor to Detroit Stoker Company, Monroe, Mich., a corporation of Michigan Application July 17, 1940, Serial No. 346,047

8 Claims.

The invention relates to stokers and forms a continuation in part of my former application bearing Serial No. 306,406 filed November 27, 1939, now matured into Patent No. 2,271,967 dated February 3, 1942. The instant application relates more particularly to stokers of that type employing sprinkler type fuel feeders together with chain grates which travel forward or in a direction reverse to that in which the fuel is .fed. The construction is applicable to stokers for relatively wide furnaces having a plurality of fuel feeders arranged in series. It is the primary object of the invention to obtain a construction for supporting and cooling these feeders, as well as introducing heated air into the combustion chamber. To this end the invention consists in the construction as hereinafter set forth.

In the drawings:

Figure l is a vertical longitudinal section through a stoker of the type to which my improvements are applied;

Figure 2 is a cross section thereof;

Figure 3 is afront elevation, partly in section on line 3-3 of Figure 1;

Figure 4 is a section similar to a portion of Figure 1 in a slightly different plane.

' With stokers of the type above referred to, the fuel is introduced into the furnace chamber through the operation of one or more fuel feeders of the rotary impeller type. Eachl of these receives the fuel from a hopper and hurls it into the combustion chamber over the grate. The grate is of the endless chain type and the portion thereof supporting the fuel, travels in a horizontal plane and in a forward direction under the combustion chamber and beyond the same into the ash receiving chamber, which is located beneath the fuel feeders. Here the chain passes around sprockets, dumping the ash, and then returns to the rear end where it passes around other sprockets into the horizontal plane.

With the construction as thus far described, the extension of the grate beneath the feeders precludes any support for the latter directly beneath the same, andit is, therefore, necessary to provide a span supported only at its opposite ends. Where the furnace is wide this span is of considerable length and constitutes a flat arch spaced above the grate only a sucient distance for the passage of the ash. It is also subjected to the heat from the combustion chamber and from the hot gases passing into the forward extension thereof beneath the arch. Thus, if a metallic beam is employed for supporting the arch there is danger of loss of rigidity due to overheating.

To provide and maintain sufficient rigidity in the arch to support the series of feeders, 1 employ a hollow box girder which also constitutes a conduit for the passage of cooling air. This conduit further serves to convey air to the individual feeders for cooling the structure thereof, after which the heated air is discharged into the furnace chamber above the grate to assist in supporting combustion.

In detail, and as shown in Figure l, A is the endless chain grate which extends around forward and rear sprockets B and B forming an upper horizontally extending portion A and a lower return portion A2. C is the combustion chamber above the greater part of the portion A and D is a at arch extending over the forward part of the portion A' to the ash receiving chamber. The arch D is carried by a hollow box girder E which is supported at its opposite ends on the side walls D5 of the furnace. A refractory lining D' is suspended from the girder and constitutes the ceiling of the ash receiving chamber. F are the feeders mounted on top of the girder E and distributed along the same, the number depending upon the width of the furnace. The detailed construction of these feeders forms no part of the present invention and, therefore, need not be described, but generally there is a hopper F for receiving the fuel, and a casing F2 beneath the same in 'which the rotary impeller (not shown) is housed. A refractory wall D2 forms the front of the furnace chamber and is provided with a flaring opening D3 through which the fuel is hurled. An apron tuyre D4 is arranged at the bottom of this aring opening.

The box girder E in addition to forming a structural support for the arch D and feeders F,

I-beam E' at the front, a channel beam E2 at the rear, a channel beam E3 extending between the Webs of the beams E and E2 and forming the bottom, and a top plate E4. The latter is provided with openings E5 registering with each of the feeders to distribute cooling air thereto. The beam E2 is of lesser height than the beam E', and above the same are channels E6 leading to the apron tuyres D4 which discharge air jets into the furnace chamber, carrying with them any fuel dust which may lodge on the apron. Also, the air which cools the feeders is discharged into the furnace chamber.

Traveling grate As previously described, the endless chain grate A has a portion A' which travels forwardly in a horizontal plane. The grate extends the full width of the furnace chamber and receives fuel deposited thereon from the several feeders supported by the hollow girder E. The grate is formed of parallelly arranged transversely extending grate bars connected to driving chains passing about the sprockets B and B'. Where the furnace chamber is of considerable width, as is the case where a plurality of feeders are required for feeding the fuel, the width of the entire grate is too great to be satisfactorily spanned by single grate bars. 'Ihis is for the reason that the heat in the center of the furnace chamber is greater than at the sides, which will cause differential expansion resulting in the warping of the bars so as to imperfectly function in relation to each other. I have, therefore, devised a construction using a plurality of parallelly arranged but independent chain grates each of relatively small Width, but together covering the whole width of the furnace chamber. The specie construction of these grates is not a part of the instant invention, but generally each grate comprises grate bars G pivotally connected at G beneath their forward edge portions to the propelling chain G2 and with their rear edge portions overlapping and resting upon a forwardly extending ledge G3 of the next grate bar in rear thereof. The opposite ends of each grate bar rest upon rails H which in turn are supported upon I-beams H forming a rigid support for holding all of the grate bars in the same horizontal plane. Thus, the grate bars in each of the chain grates are restricted in length to lessen the danger of warping or being subjected to great differences in temperature in different portions thereof. Such construction also permits of independently adjusting each chain grate to compensate for wear in the chains and the independent replacement of any bars which have been injured or do not properly function. The construction of the adjustment means is not a part of the instant invention, but is generally shown as comprising supporting inclined rails I for the return portion A2 of the grate. One of these rails I' has a pivotal support I2 at its outer end and is vertically adjustable at its opposite end, as by means of a link I3. This permits of lowering the link to increase the inclination of the bearing and the sag of the chain, so as to compensate for any elongation in the chain.

With the construction described, when the stoker is in operation, air under pressure supplied 'from any suitable source (not shown) is passed through the box girder E and is discharged therefrom through the channels E6 into the tuyres D4. Air is also discharged through a port E into the hollow walls F3 of the casing F2 containing the impeller. Furthermore, air passes through the channel Ea into a passage D8 in the casing DI which lines the flaring fuel opening D3. Thus, the air after leaving the hollow girder passes through and cools the associated metallic parts and is finally discharged into the furnace chamber above the grates. The stoker is, therefore, such that the girder is held at low enough temperature to insure its rigidity, while the air used in cooling it is discharged into the furnace chamber to support combustion.

What I claim as my invention is:

1. In a Stoker furnace, the combination with a fuel feeder and a combustion chamber into which the fuel is fed, said chamber having a portion in open communication therewith extending beneath said feeder, of a hollow girder constituting an air conduit extending transversely above said chamber portion and beneath and supporting said feeder.

2. In a stoker furnace, the combination with a fuel feeder and a combustion chamber into which the fuel is fed, said chamber having a portion in open communication therewith extending beneath said feeder, of a girder extending transversely above said chamber portion and beneath and supporting said feeder, said girder constituting a conduit through which air for cooling the structure is passed, and a connection through which a portion of the air is discharged into said feeder.

3. In a Stoker furnace, the combination with a fuel feeder of the sprinkler type, a combustion chamber into which the fuel is fed, said chamber having a portion in open communication therewith extending beneath said feeder, and a hollow perforated apron beneath said feeder extending into said combustion chamber, of a girder extending transversely beneath and supporting said fuel feeder and also constituting a conduit through which air for cooling the structure is passed, and connections with said conduit through which a portion of the air is discharged into said fuel feeder and another portion is discharged through the perforations in said hollow apron.

4. In a stoker furnace, the combination with a combustion chamber and a horizontally extending forwardly traveling grate in said chamber, of an arch above the forward portion of said grate, a fuel feeder of the sprinkler type above said arch, and a hollow girder extending transversely through said arch for supporting the same and said fuel feeder, said girder also constituting an air conduit.

5. In a stoker furnace, the combination with a series of fuel feeders of the sprinkler type and a combustion chamber having a portion extending beneath said feeders, of a hollow girder extending transversely above said chamber portion and beneath and supporting said series of feeders, being itself supported at opposite ends only, said girder constituting a conduit for cooling air.

6. In a stoker for a furnace provided with a forwardly traveling grate, the combination of a furnace chamber, a plurality of fuel feeders of the sprinkler type above a portion of said chamber, a hollow girder extending transversely above said chamber portion and beneath and supporting said feeders, said girder constituting a conduit through which air for cooling the struc# ture is passed and also an arch or span above said chamber portion supported at its opposite ends only.

7. In a stoker furnace, the combination with a combustion chamber and a horizontally extend-v ing forwardly traveling grate in said chamber, of an arch above the forward portion of said chamber and grate, a fuel feeder of the sprinkler type above said arch, a girder extending transversely through said arch for supporting the same and said fuel feeder, said beam also constituting a conduit through which air for cooling the structure is passed, and a connection to said conduit through which a portion of said air is discharged above said grate.

8. In a stoker furnace, the combination of a plurality of fuel feeders of the sprinkler type, a combustion chamber having a portion extending beneath said feeders, a hollow girder extending transversely above said chamber portion and beneath and supporting said feeders, said girder constituting a conduit through which air for cooling the structure is passed and also an arch or span supported at its opposite ends onlyI and a horizontally extending forwardly traveling 10 

